When something "dies down," it means that it becomes less intense or settles down. There are plenty of alternative words that can be used to convey the same meaning. "Fades away" and "ebbs" are two synonyms for "dies down" that refer to a gradual decrease or diminishment. "Subsides," "calms," and "quiets" all suggest a lessening of activity. "Abates," "tapers off," and "diminishes" are other synonyms that denote a decrease in intensity or severity. "Diminuendo," "dwindles," and "recedes" all imply a gradual fading away or retreat. Whether you're writing a novel or crafting a message, using synonyms for "dies down" can add depth and nuance to your writing.